Detent mechanisms are applied to control motion of components relative to each other in a manner keeping them in a defined relative position until a predetermined force is overcome suddenly allowing one of the components to move relative to the other, wherein the subsequent motion can be achieved by application of a significantly reduced force. The motion may end at another relative position defined by the detent mechanism in such a manner that a predetermined force has to be overcome to move the component back into its initial position.
Detent mechanisms are conventionally used in medicament delivery devices to control relative movement of components. For example, a detent mechanism may be used to control axial movement of a syringe relative to the delivery device to ensure that needle penetration depth is appropriate. However, given certain constraints associated with the design of medicament delivery devices (e.g., preventing component failure, ensuring safety, ensuring appropriate needle penetration depth, ensuring full delivery of medicament, etc.), there remains a need for an improved detent mechanism for a medicament delivery device.